Internet Protocol (IP) technology is designed to enable packet-switched interconnection of a heterogeneous set of computers and communication networks. A potentially diverse set of network and link layer technologies are interconnected through nodes, e.g., gateways (or routers), that provide a packet forwarding service. Information is transferred between end nodes (or hosts) as blocks of data called datagrams, where source and destination hosts are identified by fixed length addresses. Routing in IP internetworks is connectionless in nature, in that datagrams are forwarded between routers on a hop-by-hop basis using the destination address in the datagram.
Mobile IP (MIP) (Ref: IETF RFC 2002) enables an IP host, also called a “mobile node” in the context of Mobile IP, to dynamically change its point of attachment to the network, yet remain contactable via a previously given “home address”. To achieve this a temporary local address or “care of address” is associated with the mobile node when it visits a foreign network, also known as a visited network. In some cases the care of address is that of a “foreign agent” that assists in this process, while in other cases the care of address may be directly assigned to the mobile node. The care of address is registered back on the home network in a node referred to as the “home agent”. The home agent intercepts packets destined to the home address of the mobile node and redirects the packets, by means of encapsulation and tunneling, towards the care of address associated with mobile node in the visited network. Upon delivery to the care of address, the encapsulation is removed and the original packet destined to the home address is delivered to the mobile node.
Accordingly, MIP enables a moving Internet host to connect to a Foreign Agent (FA) access router in a visited network, yet still be contactable on its persistent Home Address (HoA) that it uses on its home network and is likely contained in the DNS system. This is possible because the FA gives the host a temporary local address that is either unique to the host (Co-located Care of Address or CCoA) or is unique to the FA (Care of Address or CoA). In various applications, the FA registers its CoA into the HA for the HoA address of its attached MN. The HA then tunnels packets addressed to the HoA of MN to the Care of Address (CoA) of the FA. The FA forwards packets received from the MN HoA out to the Internet as normal or reverse tunnels the packets to the Home Agent. The network features associated with the local and remote services are necessarily different given that local access services are consumed in the home network whilst remote access services are provided by a visited network in conjunction with the home network. These network features are policed typically at an access router by comparing a service profile to the actions of the attached MN. The service profile is often stored in a service profile server in the home network and therefore needs to be retrieved from the home service profile server by the access router in the home or visited network in order to provide a service corresponding to a stored profile. Two service profiles however are required to be stored in the home service profile server. This is because the local and remote access service profiles are very different reflecting the fact that the remote access service is delivered to a visited network whose offered services and policies may be very different from the home network. It also reflects the fact that the MN is not given an IP address in the visited domain that can effectively be used as an application address because the local IP address does not survive hand-offs between access routers. The Home address does however survive hand-offs due to the updated CoA from the visited network.
In summary, when an MN is on its home network, then MIP provides local access service whilst when the MN is in a visited network then MIP provides remote access service back to the home network. A deficiency of MIP is that the MN cannot get local access service from a visited domain in conjunction with remote access back to a home domain. Nor is their adequate provision for the MN to be able to support multiple remote access services concurrently from one or more third party remote networks.
In view of the above discussion, it should be apparent that there is a need for extending MIP to support both local and remote access connectivity, e.g., concurrently. One aspect of this problem is that there needs to be a way for a MN to be able to request local and/or remote access service from the local access router, and for that access router to be able to fetch the associated service profiles from the correct service profile servers in a timely manner, and in such a way that multiple commercial models between the visited, home and third party networks can be supported. Assuming the required service profiles are retrieved, the access router can then provide the requested services to the MN while making sure the MN is limited to consuming visited network resources which it is authorized to use, e.g., resources for which the visited network will be reimbursed.
An Authentication, Authorization and Accounting (AAA) system is typically used to retrieve and transport authorized service profiles to the access router. A single Network Access Identifier is normally included in a MIP message extension of a message sent to an access router when a service is being requested. The NAI includes a username part and a realm part. The realm part identifies the home service profile server whilst the username identifies the service profile(s) on that server associated with the username. When a MIP message sent to an access router includes an NAI for which that access router has no service profile, then the access router attempts to retrieve the service profile from a service profile server identified by the NAI.
The MN can have multiple NAIs associated with one or more users of the MN, but existing MIP technology only enables a single NAI to be sent in a single MIP message. Multiple profiles can be supported in the service profile server for each NAI but only one of them can be employed by the MN on any network because, currently, only local or remote access is allowed at any given time, and multiple local or multiple remote access services for a MN are not practical because of the hand-off complexities between the MN, access router and home agents.
Alternatively, in existing non-IP cellular systems, e.g., cell phone systems, whilst local and remote access may be given to the MN (cell phone), and whilst multiple concurrent remote access sessions are possible, each distinct service is requested using non-IP signaling, is provided over a unique circuit between the basestation and the gateway router to the remote network, and the service profiles (e.g. Packet Data Profiles) associated with such multiple sessions can only be retrieved from the home network of the MN. Furthermore, in such systems network service profiles are not identified by NAIs but by Access Point Names/Numbers (APNs). Furthermore, IETF AAA signaling is normally not used to retrieve such profiles.
It would be desirable if IETF AAA, MIP and/or remote access protocol signaling could be enhanced to enable an MN to use MIP signaling to signal requests for multiple concurrent services.
In view of the above discussion, it is apparent that there is a need for improved methods and apparatus for supporting end node mobility, communication session establishment and several other operations related to establishing and maintaining communications sessions in systems which use packets to transmit data.